zinnia

Zinnia is named after Johann Gottfried Zinn (1727–1759), a German botanist and anatomist who served as professor at the University of Göttingen and died at the age of 31. Zinn made significant contributions to ophthalmology — the zonule of Zinn, the circular ring of fibers that supports the eye's lens, bears his name in anatomy alongside the botanical genus. The genus was named for him by Linnaeus in 1759, the year of Zinn's death, in recognition of his botanical work and his careful description of plant anatomy. Zinn never saw a zinnia in flower; the plants are native to Mexico and the American Southwest, and European cultivation of them had barely begun during his brief life. A German anatomist who studied eyes in Göttingen is commemorated in a flower his own eyes never saw — this is the standard pathos of botanical eponymy, which regularly assigns the names of armchair naturalists to plants they never encountered.

The wild zinnias of Mexico and Central America are modest, narrow-petaled plants growing in rocky, dry terrain — nothing like the broad, densely layered, intensely colored cultivars familiar from modern gardens. The indigenous peoples of Mexico used zinnias medicinally and ceremonially; the Aztec name for the plant in Nahuatl was cempasúchil or cempoalxochitl (although this name is more specifically applied to Tagetes, the marigold, and there is some ambiguity in the botanical-historical record). Spanish colonizers described seeing Mexican plants with distinctive flower heads being sold in markets in Tenochtitlan. The Spanish brought the plant to Europe in the 16th century, where it was grown as a botanical curiosity before breeders began the systematic development that would produce the modern zinnia.

The transformation of the wild Mexican zinnia into one of the world's most popular summer annuals is a story of patient breeding across two centuries. The wild species had single-petaled, relatively small flowerheads in muted colors. German and French breeders in the late 18th and early 19th centuries selected for larger flowers and more intense color. By the mid-19th century, double-flowered varieties had been developed. The 20th century brought the great expansion of zinnia breeding in the United States, particularly through seed companies like Burpee, which introduced disease-resistant varieties and extended the color range to include the near-black ('Queen Red Lime'), near-orange, and bicolor forms. The zinnia is now available in almost every color except blue and true black, making it the most chromatically diverse of any common summer annual except the petunia.

Zinnias have a particular relationship with pollinators that has made them valuable beyond ornamental horticulture. Their composite flower heads (like all members of the daisy family, Asteraceae) are made up of tiny individual flowers called florets — the central disk florets and the outer ray florets — providing both nectar and pollen in an accessible form. In North America, zinnias are among the most important nectar sources for migrating monarch butterflies on their autumn migration through the Midwest and South to overwintering grounds in Mexico. Zinnia gardens planted along the monarch migration corridor are a documented form of wildlife corridor enhancement — the flower named for a German professor who never left Europe supporting a butterfly migration from the United States to the Mexican mountains where the zinnia's wild ancestors still grow. The circle is exact.